Fewer people are riding the subway this year — because there are fewer jobs out there.

Weekday ridership in February was down for the second consecutive month, and the drop-off is being blamed squarely on the economy, according to New York City Transit officials.

About 21,000 fewer trips were taken in February compared to the same month in 2008, agency statistics show. Average weekday ridership was about 5.1 million this February.

The numbers are “mostly the result of reduced ridership from a declining city economy,” according to the monthly financial and ridership report. Employment in the city dropped by about 2.1 percent — nearly 80,000 jobs — in the 12 months ending in February, labor statistics show.

The dismal February performance follows a January in which there were 98,000 fewer trips compared to the same month in 2008.

The lagging numbers have left New York City Transit with a $3.2 million hole in its budget. Weekday subway ridership remains up for the entire 12-month period ending in February 2009 by nearly 3 percent.

Meanwhile, transit officials said they’re extending service on the 5 line in Brooklyn.

On weekdays, the line will run to Brooklyn College/Flatbush Avenue. It currently ends at Bowling Green in lower Manhattan, making the Brooklyn leg during rush hours.